Raman spectroscopy of discrete silica supported vanadium oxide: assignment of fundamental stretching modes

Abstract

Homogeneous vanadia–silica xerogels containing vanadium loadings up to 14 mol% were investigated by Raman spectroscopy. The materials are completely amorphous and contain vanadia substituted into the continuous random network of the silica. The optical properties afford Raman spectra with very good signal to noise allowing resolution of the vanadium associated vibrational modes even at low concentrations of vanadium. From the study, assignment of the symmetric interfacial Si–O–V stretch was made at 930 cm⁻¹, and at high concentrations of vanadium the formation of V–O–V linkages was observed at 686 cm⁻¹. Also assigned was a transition associated with a perturbed silica mode at 1070 cm⁻¹.